Ventilators and related breathing circuits may be used to assist in patient breathing. For example, during surgery and other medical procedures, a patient may be connected to a ventilator to provide respiratory gases to the patient. The ventilation source may be connected into the patient's respiratory tract via an artificial airway, such as a tracheostomy tube, endotracheal tube, etc. While some breathing circuit can establish a single, direct fluid connection between the ventilator and the artificial airway, in many instances, caregivers desire the ability to introduce instruments and/or materials into the breathing circuit, for example, to insert instruments for visualization or related procedures, or to aspirate fluid or secretions from the patient's airway. Accordingly, suction catheters and suction valves may be used by caregivers in closed and open suction catheter systems to aspirate fluid or secretions (e.g., mucus, secretions, blood, foreign particles, etc.) from the patient's airway.